Event Notification Report for August 14, 2022
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
08/13/2022 - 08/14/2022
EVENT NUMBERS
56044
56044
Power Reactor
Event Number: 56044
Facility: Palo Verde
Region: 4 State: AZ
Unit: [1] [3] []
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: Joshua McDowell
HQ OPS Officer: Karen Cotton-Gross
Region: 4 State: AZ
Unit: [1] [3] []
RX Type: [1] CE,[2] CE,[3] CE
NRC Notified By: Joshua McDowell
HQ OPS Officer: Karen Cotton-Gross
Notification Date: 08/15/2022
Notification Time: 01:18 [ET]
Event Date: 08/14/2022
Event Time: 17:02 [MST]
Last Update Date: 08/15/2022
Notification Time: 01:18 [ET]
Event Date: 08/14/2022
Event Time: 17:02 [MST]
Last Update Date: 08/15/2022
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation
10 CFR Section:
50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation
Person (Organization):
O'Keefe, Neil (R4DO)
O'Keefe, Neil (R4DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
| 3 | N | Y | 100 | Power Operation | 100 | Power Operation |
VALID ACTUATIONS OF UNIT 1 AND UNIT 3 EMERGENCY DIESEL GENERATORS AND UNIT 1 AUXILIARY FEEDWATER PUMP
The following information was provided by the licensee via phone and email:
"At 1702 MST on August 14, 2022, a start-up transformer de-energized, resulting in a loss of power to the Unit 1 Train B 4.16 kV Class 1E Bus and the Unit 3 Train A 4.16 kV Class 1E Bus. The Unit 1 Train B Emergency Diesel Generator (EDG) and Unit 3 Train A EDG automatically started and energized their respective 4.16 kV Class 1E Buses. As a result of the loss of power on the Unit 1 Train B 4.16 kV Class 1E Bus, the B Auxiliary Feedwater Pump automatically started, as expected. The B Auxiliary Feedwater Pump was not needed for steam generator level control and no auxiliary feedwater valves repositioned. The B Auxiliary Feedwater Pump did not supply feedwater to the steam generators.
"This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of emergency AC electrical power systems and an auxiliary feedwater system.
"All systems operated as expected. Per the Emergency Plan, no classification was required due to the event. The 4.16 kV Class 1E Buses in Unit 2 were not affected by the de-energization of the start-up transformer since it was not aligned as normal power for Unit 2. Units 1, 2 and 3 remain in Mode 1 at 100% power.
"The cause of the start-up transformer being de-energized is under investigation. No plant transient occurred as a result of this failure.
"The NRC Resident Inspectors have been informed."
The following information was provided by the licensee via phone and email:
"At 1702 MST on August 14, 2022, a start-up transformer de-energized, resulting in a loss of power to the Unit 1 Train B 4.16 kV Class 1E Bus and the Unit 3 Train A 4.16 kV Class 1E Bus. The Unit 1 Train B Emergency Diesel Generator (EDG) and Unit 3 Train A EDG automatically started and energized their respective 4.16 kV Class 1E Buses. As a result of the loss of power on the Unit 1 Train B 4.16 kV Class 1E Bus, the B Auxiliary Feedwater Pump automatically started, as expected. The B Auxiliary Feedwater Pump was not needed for steam generator level control and no auxiliary feedwater valves repositioned. The B Auxiliary Feedwater Pump did not supply feedwater to the steam generators.
"This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of emergency AC electrical power systems and an auxiliary feedwater system.
"All systems operated as expected. Per the Emergency Plan, no classification was required due to the event. The 4.16 kV Class 1E Buses in Unit 2 were not affected by the de-energization of the start-up transformer since it was not aligned as normal power for Unit 2. Units 1, 2 and 3 remain in Mode 1 at 100% power.
"The cause of the start-up transformer being de-energized is under investigation. No plant transient occurred as a result of this failure.
"The NRC Resident Inspectors have been informed."